It only takes a spark to start a fire, and it only takes one atom to act as a seed for crystal formation. Under the right conditions, the atoms in alum will join together like puzzle pieces to form large crystals. I posted a few years ago about how to grow a large alum crystal, but this experiment is even more fun. It’s also easier for young kids, since it takes less small-motor coordination.
Alum is also called potassium aluminum sulfate. It’s used in pickling and in found in baking powder. You can grow beautiful alum crystals at home with a few jars of alum, water and any object you don’t mind covering with glue. We made fake geodes by breaking eggs in half and washing them out, but we also encrusted a grape stem and a plastic shark.
To do this experiment, you’ll need glue, 3/4 cup alum from the spice section of the grocery store (4 or 5 small jars should do it,) water and whatever you want to coat with crystals. It takes three days to complete.
On day one, paint glue on the objects you want to grow crystals on. If you’re making “geodes”, apply a thin layer of glue to the inside of an eggshell that’s been cut in half, washed out and dried. Then, sprinkle a little alum powder on the glue and let it dry overnight. We heavily coated our object with alum, but might have grown larger crystals if we’d used less. Each alum particle acts as a seed for crystal growth. The closer together they are, the less room your crystals will have to grow.
On day two, dissolve 3/4 cup alum in 2 cups of water by boiling. This step requires adult supervision. Make sure all the alum dissolves (it may still look a little cloudy) and let the solution cool. This is your supersaturated alum solution.
After about 30 minutes, when the solution is cool enough to be safely handled, gently immerse your object in the alum solution. For color, you can add a large squirt of food coloring. Let your project sit overnight to grow crystals.
On day three, gently remove your object from the alum solution and let it dry. How does it look? Draw it or take a picture to put in your science notebook!
Crystals are geometric networks of atoms. Imagine a three dimensional chain-link fence, and you’ll get the picture. Certain crystals will only grow in certain shapes. For example, diamonds are always cube-shaped when they form. Whether the atoms have joined to form a small diamond, or a large one, it will always be in the shape of a cube!
Some crystals, like alum, will form from supersaturated solutions, like the one you used in this experiment. A supersaturated solution is one that is forced to hold more atoms in water (or another solute) than it normally would. You can make these solutions using heat or pressure. Crystals can form when a supersaturated solutions encounters a “seed” atom or molecule, causing the other atoms to come out of the solution and attach to the seed.
What else could you try? Could you do the same experiment with salt, or sugar crystals? How do you think the color gets incorporated into the crystal? Do you think the food coloring disrupts the shape? Will larger crystals grow if you let your object sit in the solution longer?
You can read more about crystals and gems here.
Can kids in middle school come up with world-changing inventions? Absolutely.
Most 5-8th graders don’t have free access to labs full of chemicals and equipment, which is probably a good thing, but they’re armed with more curiosity and creativity than most adults. When given the opportunity and encouragement to let their imaginations run wild, kids come up with the most amazing ideas.
The Discovery Education 3M Young Scientist Challenge helps address the gap between idea and reality, and offers kids amazing incentives to come up with big ideas. The competition encourages kids in middle school to make two-minute videos about their ideas for using science, technology, math and engineering (STEM) to solve real-life problems. The videos are judged based on
- Creativity (ingenuity and innovative thinking) (30%);
- Scientific knowledge (30%);
- Persuasiveness and effective communication (20%); and
- Overall presentation (20%).
3M‘s Innovation Page gives overviews of how their scientists are impacting our daily lives, and some of their scientists will mentor the contest’s ten finalists, helping them envision how to take their creations from dream to reality. Ten finalists will travel to the 3M Innovation Center for the final competition.
Want to enter? Here’s the link: http://www.youngscientistchallenge.com/enter.
It seemed like the best way to learn about how kids come up with ideas was to ask my own two middle schoolers if they’d like to enter the contest, so I asked them to think about problems that they could help solve with STEM. They were less than excited until I showed them a few of the videos from the Young Scientist Challenge website. Like me, they were blown away by what Peyton Robertson and Deepika Kurup created to win the 2012 and 2013 Young Scientist Challenge and decided, without any prodding from me, that they wanted to come up with their own ideas.
My son, who is a voracious reader of all things science, and is somewhat obsessed with meteorology, immediately knew what particular area he wanted to focus on. It took a few days, but now he’s got a great idea and is working to make a model to test.
My oldest daughter was another story. She likes science, but spends much more time thinking about acting, basketball, photography, her friends, and our German Wirehaired Pointer. She quickly got frustrated and worried that she didn’t know enough about science to come up with a good idea. To encourage her, I asked her to think about how she could solve a health problem in animals, prevent basketball injuries, make a camera app, or solve an environmental problem. She decided to try to think of something people throw away and use it for something really great. While researching ocean trash, she came up with another idea, addressing a water pollution problem and is excited to test out her idea.
They need to get going, since the entry deadline is April 22nd, but I know they can do it, and love the ideas they’ve come up with!
If you’re on Twitter, you can follow the contest @DE3MYSC and join us for #STEMchat on Twitter April 8 from 9 – 10 PM Eastern as we talk about How to Raise America’s Top Young Scientist (this is the title earned by the winner of the DE 3M YSChallenge.)
Although I don’t usually write sponsored posts, I made an exception for this contest, since I think it’s a fantastic way to get kids excited about STEM. This post is sponsored by the Discovery Education 3M Young Scientist Challenge.
Today on Twin Cities Live, we did some dinosaur-related science experiments in honor of the Science Museum of Minnesota’s new Ultimate Dinosaurs exhibit.
Here are directions for doing the experiments in the video. Just click on the name to go to the post.
Spring is the season for eggs. You may prefer dyed eggs, deviled eggs, or even dinosaur eggs, if you live close to the Science Museum of Minnesota’s new Ultimate Dinosaur exhibit.
No matter what kind of eggs you like best, you’ll love these eggsperiments that let you play with the amazing architecture of eggs, dissolve their shells and even dye them with the pigments found in your refrigerator. Just click on experiments for directions and the science behind the fun!
Oil and water don’t mix, which comes in handy for this fun science experiment! Play with density and chemical reactions when you try this foaming, bubbling experiment that uses an effervescent tablet like Alka-Seltzer to make carbon dioxide bubbles ooze up through a thick layer of oil. (Adult supervision required, since Alka-Seltzer contains aspirin.)
We made these on Kare11 Sunrise News. Click here to watch.
Fill a bottle 1/4 full with water or vinegar*. Add food coloring (or red cabbage juice) to the water or vinegar.
Fill the bottle almost to the top with vegetable (or other) oil. Note how the oil floats on the water, since it’s less dense.
Finally, add an effervescent tablet to the liquid in the bottle and watch the chemical reaction. When the citric acid and sodium bicarbonate (baking soda) in the tablet react with the water and each other, they make something new: carbon dioxide gas, or CO2. The CO2 bubbles carry some of the colorful liquid up through the oil with them, but the dense liquid quickly sinks back down to the bottom.
*Vinegar reacts with the sodium bicarbonate the Alka-Seltzer, making extra carbon dioxide bubbles!
For a fun variation, put a balloon over the top of your bottle after adding the Alka-Seltzer to trap the carbon dioxide gas and inflate the balloon. If the balloon looks like it’s about to pop, remove it from the bottle.
It’s been cold in Minnesota. The governor closed all the schools today in anticipation of a high temperature of around 15 below, and a low of close to 30 below in the Twin Cities. And it gets colder as you go North. This morning on Kare 11 Sunrise, we threw boiling water in the air, froze foaming soap, blew ice bubbles and experimented with bologna at 20 below to see why tongues stick to cold metal.
We did the boiling water experiment at the cabin a few weeks ago when it was a balmy 18 below. As you can see, the low viscosity of the water, and the fact that it’s about to evaporates causes most of it to instantly freeze into a snowy fog and a shower of tiny ice crystals.
Snow, ice, wrapping paper and free time are abundant over the holidays. Here are a few fun experiments to fill the hours between celebrations. Click on the experiment name for directions.
Holiday Window Gellies: Kids of all ages love making these from gelatin and food coloring!
Snow Science: Melt snow to see how much water and dirt it contains.
Magic Ice Experiment: Lift an ice cube from a glass of water using only a string and some salt.
Wrapping Paper Egg Drop: Have a contest to see who can engineer the best egg-protecting container from left-over boxes, wrappers and decorations.
Rock Candy: Grow your own sugar crystals on a stick. What happens if you add a little peppermint oil?
What happens when food coloring molecules move, or DIFFUSE through gelatin, the substance that makes jello jiggle?
This creative science experiment that my kids and I invented lets you play with floatation physics by sprinkling glitter on melted gelatin, watch colorful dyes diffuse to create patterns and then use cookie cutters to punch out sticky window decorations. Water will evaporate from the gelatin, leaving you with paper-thin “stained glass” shapes.
You can watch us making them on Kare11 Sunrise News by clicking here.
-plain, unflavored gelatin from the grocery store or Target
-a drinking straw
*You can use the recipe below for two pans around 8×12 inches, or use large, rimmed cookie sheets for your gelatin. For a single pan, cut the recipe in half.
Step 1. Add 6 packs of plain, unflavored gelatin (1 oz or 28 gm) to 4 cups of boiling water. Stir well until all the gelatin has dissolved and remove bubbles with a spoon.
Step 2. Allow gelatin to cool to a kid-safe temperature. Pour the liquid gelatin into two large pans so it’s around 1-1.5 cm deep. It doesn’t have to be exact.
Step 5. In the pan with no glitter, use a straw to create holes in the gelatin, a few cm apart, scattered across the surface. It works best to poke a straw straight into the gelatin, but not all the way to the bottom. Spin the straw and remove it. Then, use a toothpick or skewer to pull out the gelatin plug you’ve created. This will leave a perfect hole for the food coloring. Very young children may need help.
Step 6. Add a drop of food coloring to each hole in the gelatin.
Step 7. Let the gelatin pans sit for 24 hours. Every so often, use a ruler to measure the circle of food coloring molecules as they diffuse (move) into the gelatin around them (read about diffusion at the bottom of this post.) How many cm per hour is the color diffusing? Do some colors diffuse faster than others? If you put one pan in the refrigerator and an identical one at room temperature, does the food coloring diffuse at the same rate?
Step 8. When the food coloring has made colorful circles in the gelatin, use cookie cutters to cut shapes from both pans of gelatin (glitter and food coloring), carefully remove them from the pan with a spatula or your fingers, and use them to decorate a window. (Ask a parent first, since some glitter may find its way to the floor!) Don’t get frustrated if they break, since you can stick them back together on the window.
Step 9. Observe your window jellies each day to see what happens when the water evaporates from the gelatin.
When they’re dry, peel them off the window. Are they thinner than when you started? Why? Can you re-hydrate them by soaking the dried shapes in water?
The Science Behind the Fun:
Imagine half a box filled with red balls and the other half filled with yellow ones. If you set the box on something that vibrates, the balls will move around randomly, until the red and yellow balls are evenly mixed up.
Scientists call this process, when molecules move from areas of high concentration, where there are lots of other similar molecules, to areas of low concentration, where there are fewer similar molecules DIFFUSION. When the molecules are evenly spread throughout the space, it is called EQUILIBRIUM.
Lots of things can affect how fast molecules diffuse, including temperature. When molecules are heated up, they vibrate faster and move around faster, which helps them reach equilibrium more quickly than they would if it were cold. Diffusion takes place in gases like air, liquids like water, and even solids (semiconductors for computers are made by diffusing elements into one another.)
Think about the way pollutants move from one place to another through air, water and even soil. Or consider how bacteria are able to take up the substances they need to thrive. Your body has to transfer oxygen, carbon dioxide and water by processes involving diffusion as well.
Why does glitter float on gelatin? An object’s density and it’s shape help determine its buoyancy, or whether it will float or sink. Density is an object’s mass (loosely defined as its weight) divided by its volume (how much space it takes up.) A famous scientist named Archimedes discovered that any floating object displaces its own weight of fluid. Boats have to be designed in shapes that will displace, or push, at least as much water as they weigh in order to float.
For example, a 100 pound block of metal won’t move much water out of the way, and sinks fast since it’s denser than water. However , a 100 pound block of metal reshaped into a boat pushes more water out of the way and will float if you design it well!
What is the shape of your glitter? Does it float or sink in the gelatin?
Here’s a video I made for KidScience app that demonstrates how to make window gellies
Credit: My 11 YO daughter came up with the brilliant idea to stick this experiment on windows. I was just going to dry out the gelatin shapes to make ornaments. Kids are often way more creative than adults!
Thanksgiving isn’t the same without cranberries. This year, pick up an extra bag for this fun science experiment.
With cranberries and baking soda, you can create invisible messages that will be revealed to friendly eyes and self-destruct before your enemies have a chance to read them. You’ll see how some pigments in fruit can change color when they’re exposed to an acid or a base. *I discovered that some paper will turn blue in cranberry juice, so test the type of paper you want to use by first dipping a small piece it in the cranberry juice (before you start writing messages!) It should turn pink, not blue. Otherwise, you won’t be able to see your message!
-half a bag of cranberries
-a homemade pen: To write your message, you’ll also want to find a small paintbrush, Q-tip, or something else with an absorbent tip. We had the best luck using cake-pop sticks or cotton swabs cut in half (non-cotton end) as pens.
Have an adult or teenager boil the cranberries in about three cups of water for 15 or 20 minutes. Be sure to put a lid on the pan, since the small pockets of air that help cranberries float can make them explode as they cook. If you listen, you’ll hear some of the them popping! Crush the cooked berries and push the liquid through a sieve or colander to collect the concentrated cranberry juice. Most cranberry juice from the grocery store is diluted with water, corn syrup and other juices and won’t work as well!
Let the juice cool and pour it into a casserole dish or cake pan that the paper you’re writing your messages on will fit into. If your cranberry juice seems thick and syrupy, add a little water (maybe half a cup.) It has to have enough water in it so that it will soak into the paper!
To make your invisible ink, add a few teaspoons of baking soda to about 1/3 cup of warm water and dissolve it as well as you can. Don’t worry if you can still see some baking soda. Using your homemade writing tool, use the baking soda solution to write a message on your paper. It may take a little practice, so don’t get frustrated. You’ll get the hang of it!
Let your message air dry, or speed things up with a blow dryer.
To reveal your message, float and then submerge your paper in the cranberry juice and see what happens!
The science behind the fun:
Cranberries contain pigments called anthocyanins (an-tho-SY-a-nins), which give them their bright color. In nature, these pigments attract birds and other animals to fruit. This is important because animals eat the berries and spread plants seeds from one place to another.
These pigments, called flavanoids, change color when they come in contact with acids and bases. Cranberry juice is very acidic, and the pigment is red in acids. When you add it to a base, it turns purple or blue. Baking soda is a base, so your baking soda message will turn blue when it comes into contact with the pigments in the cranberry juice. Eventually, when enough cranberry juice soaks into the paper, it will dilute the baking soda and make the paper acidic, turning the pigment back to red and your message will disappear!
There are over 300 kinds of anthocyanins which are found in many fruits and vegetables including blueberries, red cabbage, grapes and blueberries. Scientists think they may have many health benefits and some researchers are even making organic solar cells using flavanoids!
Enrichment: What other juices can you use to reveal secret messages? What else could you use as ink? If you use lemon juice as ink, does it turn a different color?
Try making your own recipe for spy juice! I’d love to hear how red cabbage works! Check out my red cabbage litmus paper experiment to find out how to make red cabbage juice.
-a glass bottle, like a juice bottle, whose neck is a little smaller than a hard-boiled egg
-small or medium-sized hard-boiled eggs, peeled
-a long match or lighter
1. Decorate your bottle to look like a monster, with the mouth of the bottle on the mouth-end of the monster
2. Put one or two birthday candles in the wide end of a hard-boiled egg.
3. Light the candles and hold them under the inverted bottle to warm the air inside.
4. Hold your bottle upside down and put the candle end of the egg up into the bottle so it forms a seal. Continue to hold the egg until the candle goes out and the egg is “pushed” into the bottle by atmospheric pressure, which is the weight of the air pushing down on the egg.
The flame from the candle heats the air in the bottle. When the candle goes out from lack of oxygen, the remaining air in the bottle cools rapidly, decreasing the air pressure in the bottle and creating a partial vacuum. The outside air, whose atmospheric pressure is higher, pushes the egg into the bottle as it attempts to equalize the pressure inside of the bottle.